Oscillating heat treatment method for a superalloy

ABSTRACT

Superalloy solidified in a directional manner often cannot be subjected to heat treatment because the heat treatment leads to recrystallization. As a result of the temperature profile during a heat treatment according to the invention which oscillates in the manner of a pendulum, a recrystallization during heat treatment can be avoided because mechanical stresses are reduced thanks to the recurring succession of dissolutions and precipitations of the precipitate. The method can be applied to a Ni-based superalloy with γ-precipitates. After the cyclic heat treatment, the temperature can be adjusted to and maintained at a temperature which is the same as or higher than the complete dissolution temperature. An oscillating movement can also take place above the complete dissolution temperature.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is the US National Stage of International ApplicationNo. PCT/EP2007/052461, filed Mar. 15, 2007 and claims the benefitthereof. The International Application claims the benefits of Europeanapplication No. 06008688.1, filed Apr. 26, 2006, both of theapplications are incorporated by reference herein in their entirety.

FIELD OF THE INVENTION

The invention relates to a heat treatment method for a material whichhas a precipitate.

BACKGROUND OF THE INVENTION

Nickel-based superalloys which are used particularly for gas turbinecomponents, such as turbine blades or combustion chamber inserts, have aγ-phase which, within the framework of a repair, that is to say duringrefurbishment, is subjected to what is known as γ-solution annealing inorder to restore the original material properties.

This is not possible without difficulty in components havingdirectionally solidified nickel-based superalloys. γ-solution annealingleads in the case of a mechanically deformed surface, such as, forexample, in the region of the moving blade feet, to a recrystallizationof the γ-phase on the component surface. Since, in contrast toconventional nickel-based superalloys, directionally solidifiednickel-based superalloys have no or only few elements consolidating thegrain boundaries, the grain reformation, caused by recrystallization, onthe component surface is an unacceptable material weakening.

SUMMARY OF THE INVENTION

The object of the invention, therefore, is to overcome theabovementioned problem.

The object is achieved by a heat treatment method according to theindependent claim, in which, by dissolving the precipitate,precipitating the precipitate and, once again, dissolving andprecipitation, the mechanical stresses are reduced, so that norecrystallization can occur.

The dependant claims list further advantageous measures which mayadvantageously be combined with one another in any desired way.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawing:

FIGS. 1-12 show exemplary embodiments of the temperature profile of heattreatment methods according to the invention,

FIG. 13 shows a list of superalloys,

FIG. 14 shows a gas turbine,

FIG. 15 shows a turbine blade in perspective, and

FIG. 16 shows a combustion chamber in perspective.

DETAILED DESCRIPTION OF THE INVENTION

The heat treatment according to the invention is carried out, inparticular, for nickel-based superalloys. Such DX or SX nickel-basedsuperalloys (FIG. 13) are used, in particular, for turbine blades 120,130 (FIG. 14, 15) and combustion chamber elements 155 (FIG. 16) forturbines, in particular for gas turbines 100 (FIG. 14).

The heat treatments may also be carried out with aircraft turbinecomponents (in particular, blades).

By way of example, the method of heat treatment of nickel superalloys,which have the γ-phase, is explained, that is to say γ-solutionannealing.

Before heat treatment, fluoride ion cleaning (FIC) may also be carriedout, which may be utilized, on the one hand, in order to clean oxidesfrom cracks, but also in order, in particular, to deplete the componentsurface of metallic elements of the material of the substrate, inparticular of aluminum and/or titanium, such as superalloys, since thesetwo elements are γ-formers. A depletion of the γ-phase of superalloys inthe region of the component surface lowers the inherent stresses whichhave occurred in the surface due to mechanical load. By this stressbeing lowered, the motive force for grain reformation(recrystallization) is reduced.

The FIC cleaning required for this purpose is preferably carried out attemperatures of around 1000° C. by means of HF/H₂ mixtures.

The γ-solution annealing for the complete dissolving of the precipitate(here γ) according to the prior art has for superalloys a γ-fullsolution annealing temperature T_(LG) which is calculated according tothe following formula:

T_(LG)=1229.315+3.987 W−3.624 Ta+2.424 Ru+0.958 Re−6.362 Cr−4.943Ti−2.602 Al−2.415 Co−2.224 Mo.

The solution annealing temperature profile in time T(t) is dealt withbelow.

In the figures, the temperature profile T(t) is plotted against the timet, the temperature T_(LG) representing the full solution annealingtemperature described above, and the dissolution temperature T_(SOLV)representing a material-specific temperature beyond which theprecipitate can first be dissolved, but a complete dissolution of theprecipitates lasts too long.

The time duration t1, preferably at least 1 h, is the time from when thetemperature T_(SOLV) is first overshot to the time point t3 from whichthe temperature T dwells, preferably constant, at the full solutionannealing temperature T_(LG). The dwell duration at the full solutionannealing temperature preferably amounts to at least 1 hour (1 h).

In FIG. 1, the oscillating movement of the temperature T commences evenbelow the temperature T_(SOLV) and then rises continuously (see thedashed ascending line) and in an oscillating manner to the temperatureT_(LG).

After overshooting the temperature T_(SOLV), the temperature T_(SOLV)can be undershot due to the oscillating movement (not the case in FIG.1).

Preferably from a specific time t3, the temperature T dwells, constant,at the full solution annealing temperature T_(LG) at which it dwellspreferably for at least 1 h.

In FIG. 1, four local maxima of the temperature profile can be seen,that is to say four oscillating movements are present. However, evenfive or more oscillating movements may be generated.

In FIG. 2, the temperature profile is similar to that in FIG. 1, but theoscillating movement commences only above the temperature T_(SOLV). Thetemperature T_(SOLV) is preferably not undershot due to the oscillatingmovement.

Preferably from a specific time t3, the temperature T dwells, constant,at the full solution annealing temperature T_(SOLV) at which it dwellspreferably for at least 1 h.

In FIG. 2, three local maxima can be seen, so that, here, threeoscillating movements are present.

In FIG. 3, the temperature T rises (not in an oscillating manner) abovethe temperature T_(SOLV) and here falls again, for example once, belowthe temperature T_(SOLV) and then rises in an oscillating manner up tothe temperature T_(LG).

Preferably from a specific time t3, the temperature T dwells, constant,at the full solution annealing temperature T_(LG) at which it dwellspreferably for at least 1 h.

Three local maxima can be seen in FIG. 3, so that, here, threeoscillating movements are present.

In the continuously rising oscillating movement (see the dashed lines)of the temperature T according to FIGS. 1, 2 and 3, the temperature mayoscillate once or more than once from a temperature above T_(SOLV) tobelow the temperature T_(SOLV).

In FIG. 4, the temperature T rises (not in an oscillating manner) abovethe temperature T_(SOLV) to the solution annealing temperature T_(LG)and oscillates to and fro between these two temperatures T_(LG),T_(SOLV).

The oscillating temperature profile T(t) then preferably runs uniformly,as can be seen from the dashed line running horizontally.

Preferably from a specific time t3, the temperature T dwells, constant,at the full solution annealing temperature T_(LG) at which it preferablydwells for at least 1 h.

FIG. 4 illustrates two oscillating movements. However, three or moreoscillating movements may be carried out.

In FIG. 5, the temperature T also rises (not in an oscillating manner)to the full solution annealing temperature T_(LG) and then falls,although the temperature T_(SOLV) is not reached (difference ΔT>0).

The oscillating temperature profile T(t) then preferably runs uniformly,as can be seen from the dashed line running horizontally.

Preferably from a specific time t3, the temperature T dwells, constant,at the full solution annealing temperature T_(LG) at which it dwellspreferably for at least 1 h.

Three local maxima can be seen in FIG. 5, and therefore, here, threeoscillating movements are present.

In FIG. 6, the temperature T rises (not in an oscillating manner) beyondthe temperature T_(SOLV) to a temperature below the temperature T_(LG)and then oscillates to and fro between these two values. The oscillatingtemperature profile T(t) then preferably runs uniformly, as can be seenfrom the dashed line running horizontally.

Preferably from a specific time t3, the temperature T dwells, constant,at the full solution annealing temperature T_(LG) at which it dwellspreferably for at least 1 h.

FIG. 6 illustrates two oscillating movements. However, even three ormore oscillating movements may be carried out.

In FIG. 7, the temperature T rises (not in an oscillating manner) beyondthe temperature T_(SOLV) to a temperature below the temperature T_(LG)and oscillates to and fro between this temperature below T_(LG) and atemperature above T_(SOLV). The oscillating temperature profile T(t)then preferably runs uniformly, as can be seen from the dashed linerunning horizontally.

Preferably from a specific time t3, the temperature T dwells, constant,at the full solution annealing temperature T_(LG) at which it dwellspreferably for at least 1 h.

Three local maxima can be seen in FIG. 7, and therefore, here, threeoscillating movements are present.

In contrast to FIGS. 4 and 6, the temperature T in FIGS. 8 and 9 alsooscillates below the temperature T_(SOLV).

In FIG. 8 the temperature always reaches a maximum value of the fullsolution annealing temperature T_(LG), whereas, in FIG. 9, the maximumvalue of the temperature profile reaches a temperature above T_(SOLV,)but below the full solution annealing temperature T_(LG).

Preferably from a specific time t3, the temperature T in FIGS. 8 and 9dwells, constant, at the full solution annealing temperature T_(LG) atwhich it dwells preferably for at least 1 h.

FIG. 8 illustrates two oscillating movements. However, even three ormore oscillating movements may be carried out.

FIG. 9 illustrates two oscillating movements. However, even three ormore oscillating movements may be carried out.

In FIG. 10, the temperature T rises (not in an oscillating manner) abovethe temperature T_(SOLV) and oscillates to and fro between this valueand a lower value (≧T_(SOLV)). The oscillating temperature profile T(t)then preferably runs uniformly, as can be seen from the dashed linerunning horizontally.

Thereafter, after a specific time t2, the temperature rises, inparticular in an oscillating manner, to the full solution annealingtemperature T_(LG).

Preferably from a specific time t3, the temperature T dwells, constant,at the full solution annealing temperature T_(LG) at which it dwellspreferably for at least 1 h.

In FIG. 10, four local maxima are present, and therefore fouroscillating movements occur. However, even five or more oscillatingmovements may be carried out.

FIG. 12 illustrates a further exemplary embodiment of the oscillatingtemperature profile T(t) according to the invention.

The average value of the temperature T about which the temperaturefluctuates is increased in steps here until, from a time t3, thetemperature is set, constant, at a temperature T_(LG).

Initially, the temperature T oscillates about the temperature T_(SOLV),then rises to a higher temperature, so that the temperature T_(SOLV) ispreferably no longer undershot, oscillates and rises further again in athird or in further steps, the maximum temperature T_(LG) being reachedhere or a clearance with respect to the temperature T_(LG) beingpresent.

Preferably from a specific time t3, the temperature T dwells, constant,at the full solution annealing temperature T_(LG) at which it dwellspreferably for at least 1 h.

FIGS. 1 to 12 illustrate the oscillating movements only preferably inwavy or sinusoidal form, but they may also be formed triangularly (FIG.11), rectangularly (not illustrated) or otherwise.

Likewise, in the oscillating movements, the temperature T_(LG) may alsobe reached or overshot once or more than once by means of theoscillating movement.

After the end of the oscillating movement, the temperature can be set ata temperature equal to or higher than the full solution annealingtemperature T_(LG) and be held there, in particular for at least onehour.

If a temperature higher than the full solution annealing temperatureT_(LG) is set at the end in a specific time t3, an oscillating movementabove the full solution annealing temperature T_(LG) may preferably takeplace.

It is also advantageous if the full solution annealing temperature isnot overshot, apart from an unwanted overshooting when the temperatureis being set to the full solution annealing temperature.

It is also advantageous that the temperature rises in an oscillatingmanner. The oscillating rise of the temperature T in FIGS. 1, 2, 3 and10 takes place at least intermittently, in particular at least duringthe overshooting of the temperature T_(SOLV).

In particular, the oscillating rise in the temperature T is followed bya holding time at a temperature ≧ of the full solution annealingtemperature T_(LG).

The oscillating rise in the temperature can be seen from the dashed linewhich rises, the temperature of a maximum of the oscillating movementbeing increased in relation to the maximum of the preceding maximum.Correspondingly, the minima, that is to say the valleys of theoscillating movement, are not identical, but rise with the time t.

FIG. 13 shows a list of nickel-based DS or SX superalloys which can betreated by means of the method according to the invention.

For the material IN 6203 DS, the temperature T_(SOLV) amounts to 1100°C. and the temperature T_(LG) to 1150° C.

For the material IN 792 DS, the temperature T_(SOLV) amounts to 1140° C.and the temperature T_(LG) to 1230° C.

The material PWA 1483 SX has a temperature T_(SOLV) of 1150° C. and atemperature T_(LG) of 1250° C.

FIG. 14 shows a gas turbine 100 by way of example in a longitudinal partsection.

The gas turbine 100 has inside it a rotor 103 rotary-mounted about anaxis of rotation 102 and having a shaft 101, said rotor also beingdesignated as a turbine rotor.

An intake casing 104, a compressor 105, a, for example, toroidalcombustion chamber 110, in particular annular combustion chamber, with aplurality of coaxially arranged burners 107, a turbine 108 and theexhaust gas casing 109 succeeding one another along the rotor 103.

The annular combustion chamber 110 communicates with a, for example,annular hot-gas duct 111. There, for example, four turbine stages 112connected one behind the other form the turbine 108.

Each turbine stage 112 is formed, for example, from two blade rings. Asseen in the direction of flow of a working medium 113, a guide blade row115 is followed in the hot-gas duct 111 by a row 125 formed from movingblades 120.

The guide blades 130 are in this case fastened to an inner casing 138 ofa stator 143, whereas the moving blades 120 of a row 125 are mounted onthe rotor 103, for example, by means of a turbine disk 133. A generatoror a working machine (not illustrated) is coupled to the rotor 103.

While the gas turbine 100 is in operation, air 135 is sucked in by acompressor 105 through the intake casing 104 and is compressed. Thecompressed air provided at the turbine-side end of the compressor 105 isrouted to the burners 107 and is mixed there with a fuel. The mixture isthen burnt in the combustion chamber 110 so as to form the workingmedium 113.

The working medium 113 flows from there along the hot-gas duct 111 pastthe guide blades 130 and the moving blades 120. At the moving blades120, the working medium 113 expands so as to transmit a pulse, so thatthe moving blades 120 drive the rotor 103 and the latter drives theworking machine coupled to it.

The components exposed to the hot working medium 113 are subject tothermal loads while the gas turbine 100 is in operation. The guideblades 130 and moving blades 120 of the first turbine stage 112, as seenin the direction of flow of the working medium 113, are subjected to thehighest thermal load, in addition to the heatshield elements lining theannular combustion chamber 110.

In order to withstand the temperatures prevailing there, these bladesmay be cooled by means of a coolant.

Likewise, substrates of the components may have a directional structure,that is to say they are monocrystalline (SX structure) or have onlylongitudinally directed grains (DS structure).

The material used for the components, particularly for the turbine blade120, 130 and components of the combustion chamber 110, is, for example,iron-, nickel- or cobalt-based superalloys.

Such superalloys are known, for example, from EP 1 204 776 B1, EP 1 306454, EP 1 319 729 A1, WO 99/67435 or WO 00/44949; these publications arepart of the disclosure with regard to the chemical composition of thealloys.

The guide blade 130 has a guide blade foot (not illustrated here) facingthe inner casing 138 of the turbine 108 and a guide blade head lyingopposite the guide blade foot. The guide blade head faces the rotor 103and is secured to a fastening ring 140 of the stator 143.

FIG. 15 shows a perspective view of a moving blade 120 or guide blade130 of a turbomachine which extends along a longitudinal axis 121.

The turbomachine may be a gas turbine of an aircraft or of a powerstation for electricity generation, a steam turbine or a compressor.

The blade 120, 130 has successively along the longitudinal axis 121 afastening region 400, a blade platform 403 contiguous to the latter andalso a blade leaf 406 and a blade tip 415.

As a guide blade 130, the blade 130 may have (not illustrated) a furtherplatform at its blade tip 415.

In the fastening region 400, a blade foot 183 is formed which serves(not illustrated) for fastening the moving blades 120, 130 to a shaft ora disk. The blade foot 183 is configured, for example, as a hammer head.Other configurations as a pinetree or dovetail foot are possible. Theblade 120, 130 has a leading edge 409 and a trailing edge 412 for amedium which flows past the blade leaf 406.

In conventional blades 120, 130, for example, solid metallic materials,in particular superalloys, are used in all regions 400, 403, 406 of theblade 120, 130. Such superalloys are known, for example, from EP 1 204776 B1, EP 1 306 454, EP 1 319 729 A1, WO 99/67435 or WO 00/44949; thesepublications are part of the disclosure with regard to the chemicalcomposition of the alloy.

The blade 120, 130 may in this case be manufactured by means of acasting method, also by means of a directional solidification, by aforging method, by a milling method or combinations of these.

Workpieces with a monocrystalline structure or structures are used ascomponents for machines which are exposed to high mechanical, thermaland/or chemical loads during operation.

The manufacture of monocrystalline workpieces of this type takes place,for example, by directional solidification from the melt. These arecasting methods in which the liquid metallic alloy solidifies into themonocrystalline structure, that is to say into the monocrystallineworkpiece, or directionally solidifies.

In this case, dendritic crystals are oriented along the heat flow andform either a columnar-crystalline grain structure (columnar, that is tosay grains which run over the entire length of the workpiece and here,according to general linguistic practice, are designated as beingdirectionally solidified) or a monocrystalline structure, that is to saythe entire workpiece consists of a single crystal. These methods mustavoid the transition to globulitic (polycrystalline) solidification,since, due to undirected growth, transverse and longitudinal grainboundaries are necessarily formed which nullify the good properties ofthe directionally solidified or monocrystalline component.

When directionally solidified structures are referred to in generalterms, this means both monocrystals which have no grain boundaries or atmost small-angle grain boundaries and columnar-crystal structures whichhave grain boundaries running in the longitudinal direction, but notransverse grain boundaries. In the case of these second-mentionedcrystalline structures, directionally solidified structures are alsoreferred to.

Such methods are known from U.S. Pat. No. 6,024,792 and EP 0 892 090 A1;these publications are part of the disclosure with regard to thesolidification method.

The blades 120, 130 may likewise have coatings against corrosion oroxidation, for example (MCrAlX; M is at least one element of the groupiron (Fe), cobalt (Co), nickel (Ni), X is an active element and standsfor yttrium (Y) and/or silicon and/or at least one rare earth element,or hafnium (HO). Such alloys are known from EP 0 486 489 B1, EP 0 786017 B1, EP 0 412 397 B1 or EP 1 306 454 A1 which are to be part of thedisclosure with regard to the chemical composition of the alloy.

The density is preferably around 95% of the theoretical density.

A protective aluminum oxide layer (TGO=thermal grown oxide layer) isformed on the MCrAlX layer (as an intermediate layer or as the outermostlayer).

On the MCrAlX, a heat insulation layer may also be present, which ispreferably the outermost layer and consists, for example, of ZrO₂,Y₂O₃—ZrO₂, that is to say it is not or is partially or is completelystabilized by yttrium oxide and/or calcium oxide and/or magnesium oxide.The heat insulation layer covers the entire MCrAlX layer.

By means of suitable coating methods, such as, for example, electronbeam evaporation (EB-PVD), columnar grains are generated in the heatinsulation layer.

Other coating methods may be envisaged, for example atmospheric plasmaspraying (APS), LPPS, VPS or CVD. The heat insulation layer may haveporous microcrack- or macrocrack-compatible grains for better thermalshock resistance. The heat insulation layer is therefore preferably moreporous than the MCrAlX layer.

The blade 120, 130 may be hollow or solid. If the blade 120, 130 is tobe cooled, it is hollow and, if appropriate, also has film-cooling holes418 (indicated by dashes).

FIG. 16 shows a combustion chamber 110 of the gas turbine 100. Thecombustion chamber 110 is configured, for example, as what is known asan annular combustion chamber, in which a multiplicity of burners 107arranged around an axis of rotation 102 in the circumferential directionissue into a common combustion chamber space 154 and generate the flames156. For this purpose, the combustion chamber 110 is configured in itsentirety as an annular structure which is positioned around the axis ofrotation 102.

To achieve comparatively high efficiency, the combustion chamber 110 isdesigned for a comparatively high temperature of the working medium M ofabout 1000° C. to 1600° C. In order to make it possible to have acomparatively long operating time even in the case of these operatingparameters which are unfavorable for the materials, the combustionchamber wall 153 is provided on its side facing the working medium Mwith an inner lining formed from heatshield elements 155.

On account of the high temperatures inside the combustion chamber 110,moreover, a cooling system may be provided for the heatshield elements155 or for their holding elements. The heatshield elements 155 are then,for example, hollow and, if appropriate, also have cooling holes (notillustrated) issuing into the combustion chamber space 154.

Each heatshield element 155 consisting of an alloy is equipped on theworking medium side with a particularly heat-resistant protective layer(MCrAlX layer and/or ceramic coating) or is manufactured from materialresistant to high temperature (solid ceramic bricks).

This protective layer may be similar to those of the turbine blades,that is to say, for example, MCrAlX means: M is at least one element ofthe group iron (Fe), cobalt (Co), nickel (Ni), X is an active elementand stands for yttrium (Y) and/or silicon and/or at least one rare earthelement or hafnium (Hf). Such alloys are known from EP 0 486 489 B1, EP0 786 017 B1, EP 0 412 397 B1 or EP 1 306 454 A1 which are to be part ofthe disclosure with regard to the chemical composition of the alloy.

On the MCrAlX, a, for example, ceramic heat insulation layer may also bepresent and consist, for example, of ZrO₂, Y₂O₃—ZrO₂, that is to say itis not or is partially or is completely stabilized by yttrium oxideand/or calcium oxide and/or magnesium oxide.

By means of suitable coating methods, such as, for example, electronbeam evaporation (EB-PVD), columnar grains are generated in the heatinsulation layer.

Other coating methods may be envisaged, for example atmospheric plasmaspraying (APS), LPPS, VPS or CVD. The heat insulation layer may haveporous microcrack- or macrocrack-compatible grains for better thermalshock resistance.

Refurbishment means that turbine blades 120, 130 and heatshield elements155, after their use, must, where appropriate, be freed of protectivelayers (for example, by sandblasting). A removal of the corrosion and/oroxidation layers or products is then carried out. In solution annealing,the method according to the invention is used. If appropriate, cracks inthe turbine blade 120, 130 or in the heatshield element 155 are alsorepaired. A recoating of the turbine blades 120, 130 and heatshieldelements 155 and a renewed use of the turbine blades 120, 130 or of theheatshield elements 155 then take place.

1.-28. (canceled)
 29. A method for heat treating a material having aprecipitate that is dissolvable at least partially in a matrix of thematerial above a dissolution temperature, comprising: at leasttemporarily heat treating the material above the dissolution temperaturevia a temperature profile; and at least temporarily oscillating thetemperature profile for the heat treatment.
 30. The method as claimed inclaim 29, wherein the temperature profile oscillates below thedissolution temperature and continues to increase at least temporarilyabove the dissolution temperature.
 31. The method as claimed in claim29, wherein the temperature profile oscillates above the dissolutiontemperature.
 32. The method as claimed in claim 29, wherein thetemperature profile initially rises to a temperature below thedissolution temperature and further oscillately rises.
 33. The method asclaimed in claim 29, wherein the temperature profile initially rises atleast to the dissolution temperature and further oscillately rises. 34.The method as claimed in claim 29, wherein the temperature profileoscillates initially once or more than once from a temperature above thedissolution temperature to a temperature below the dissolutiontemperature.
 35. The method as claimed in claim 29, wherein thetemperature profile oscillates from a temperature above the dissolutiontemperature to a temperature not below the dissolution temperature. 36.The method as claimed in claim 29, wherein the oscillation is betweentwo local maxima in the temperature profile and the temperature profilecomprises at least two oscillations.
 37. The method as claimed in claim29, wherein the temperature profile oscillates for at least one hour.38. The method as claimed in claim 29, wherein the temperature profileoscillates sinusoidally or triangularly.
 39. The method as claimed inclaim 29, wherein the precipitate is dissolved completely in the matrixat a full solution annealing temperature.
 40. The method as claimed inclaim 39, wherein the temperature profile oscillates between: thedissolution temperature and the full solution annealing temperature, ora temperature above the dissolution temperature and the full solutionannealing temperature, or the dissolution temperature and a temperaturebelow the full solution annealing temperature, or a temperature abovethe dissolution temperature and a temperature below the full solutionannealing temperature, or a temperature below the dissolutiontemperature and the full solution annealing temperature.
 41. The methodas claimed in claim 39, wherein the temperature profile initially risesto a temperature below the dissolution temperature and furtheroscillately rises to the full solution annealing temperature.
 42. Themethod as claimed in claim 39, wherein the temperature profile reachesthe full solution annealing temperature during the oscillation at aspecific time and is set constant at the full solution annealingtemperature for the specific time.
 43. The method as claimed in claim42, wherein the temperature profile stays at the full solution annealingtemperature for at least one hour.
 44. The method as claimed in claim39, wherein the temperature profile is set constant at a temperatureabove the full solution annealing temperature at a specific time. 45.The method as claimed in claim 39, wherein the temperature profileovershoots the full solution annealing temperature at a specific time.46. The method as claimed in claim 29, wherein the temperature profiledoes not overshoot the full solution temperature.
 47. The method asclaimed in claim 29, wherein a metallic element of the material isdepleted before the heat treatment.
 48. The method as claimed in claim29, wherein the precipitate is a γ-phase of a nickel-based superalloy.